CN116230400B

CN116230400B - Power capacitor

Info

Publication number: CN116230400B
Application number: CN202310342102.0A
Authority: CN
Inventors: 谢志懋; 劳武烈; 王占东
Original assignee: Foshan City Xinyuan Electronics Co ltd
Current assignee: Foshan City Xinyuan Electronics Co ltd
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2023-09-05
Anticipated expiration: 2043-03-31
Also published as: CN116230400A

Abstract

The application belongs to the technical field of power capacitors, and discloses a power capacitor, which comprises: the capacitor comprises a containing shell, a sealing cover, a first lead-out tab, a second lead-out tab, a first lead, a second lead, a first detection column, a second detection column, a detection wire, a capacitor core body and surface insulation paper; the surface insulating paper is used for wrapping the outer peripheral surface of the capacitor core body. According to the application, the first detection column and the second detection column are arranged, and the detection wire is wound around the capacitor core body, so that the judgment of the health condition of the capacitor core body is realized by judging whether the detection wire is disconnected or not. Thereby realizing rapid judgment of the internal condition of the power capacitor. When the inside of power capacitor goes wrong, can learn fast through first detection post and second detection post, the detection circuit of outside of being convenient for in time breaks off the power capacitor and external load's electric connection. Thereby avoiding the influence of the power capacitor on the external load.

Description

Power capacitor

Technical Field

The application belongs to the technical field of capacitors, and particularly relates to a power capacitor.

Background

The power capacitor in the prior art generally includes a case, a core body, and lead-out electrode terminals. Wherein, the core falls into the inside of casing, and extraction electrode terminal draws forth from the inside of casing. The core is formed by rolling a composite film.

Since the power capacitor generally has a large power, the load is easily affected when the power capacitor is unstable. However, the power capacitor is generally packaged by the shell, so that the specific situation of the power capacitor cannot be known well in time, and hidden danger is easily brought to the use of the power capacitor.

Therefore, how to know the internal condition of the power capacitor in time is a technical problem that needs to be studied in the industry.

Disclosure of Invention

The present application is directed to a power capacitor that solves one or more of the problems of the prior art, and at least provides a useful choice or creation of conditions.

In order to solve the technical problems, the application provides a power capacitor. Specifically, a power capacitor includes: the capacitor comprises a containing shell, a sealing cover, a first lead-out tab, a second lead-out tab, a first lead, a second lead, a first detection column, a second detection column, a detection wire, a capacitor core body and surface insulation paper; the surface insulating paper is used for wrapping the outer peripheral surface of the capacitor core body;

the first lead-out tab, the second lead-out tab, the first detection column and the second detection column are embedded into the sealing cover, the capacitor core falls into the accommodating shell, and the capacitor core comprises a first polypropylene composite film and a second polypropylene composite film; the first polypropylene composite film and the second polypropylene composite film are parallel and coaxially rolled to form a capacitor roll shape;

the first polypropylene composite film comprises: a first polypropylene-based film, the surface side of which is plated with a first metal layer; the second polypropylene composite film includes: a second polypropylene-based film, the surface side of which is plated with a second metal layer; the first polypropylene-based film and the second polypropylene-based film are wound in parallel and in the same direction, wherein the second polypropylene-based film is positioned between the second metal layer and the first metal layer; the first metal layer is connected with the first lead-out tab through a first lead wire, and the second metal layer is connected with the second lead-out tab through a second conductor; one end of the detection wire is connected with the first detection column, and the other end of the detection wire is wound along the surface insulating paper on the peripheral wall of the capacitor core body and is finally connected with the second detection column; the cover seals the accommodating case.

Further, the first detection column is made of copper alloy.

Further, the second detection column is made of copper alloy.

Further, a first through hole is formed in the first lead-out tab.

Further, a second through hole is formed in the second lead-out tab.

Further, the preparation method of the first polypropylene-based film is the same as the preparation method of the second polypropylene-based film, and specifically comprises the following steps:

(1) Mixing and dispersing carbon nano tubes, nano silicon dioxide, nano silicon carbide and butyl titanate to prepare a mixture;

(2) And (2) mixing polypropylene, polyethylene and an acrylonitrile-butadiene-styrene copolymer, heating to a molten state, adding the mixture prepared in the step (1) and a silane coupling agent, stirring for dispersion, pressurizing, extruding, cooling, and performing biaxial stretching to prepare the first polypropylene-based film.

Further, in the step (1), the weight ratio of the carbon nanotubes, the nano silicon dioxide, the nano silicon carbide and the butyl titanate is 0.1: (1-5): (0.1-1): (1-10); the preferable weight ratio is 0.1: (3-4): (0.2-0.8): (3-10).

In the step (1), the stirring speed of mixing and dispersing is 1000-3000 r/min, and the mixing and dispersing time is 1-2 hours.

Further, in the step (1), the temperature of the mixed dispersion is 150 to 200 ℃, preferably 180 to 190 ℃.

Further, in the step (2), the weight ratio of polypropylene, polyethylene and acrylonitrile-butadiene-styrene copolymer is 100: (20-30): (20-40); the preferable weight ratio is 100: (25-30): (20-30).

Further, in the step (2), the weight ratio of the polypropylene, the mixture prepared in the step (1) and the silane coupling agent is 100: (10-30): (8-35); the preferable weight ratio is 100: (10-18): (12-30).

Further, in the step (2), the stirring and dispersing speed is 3000-5000 rpm, and the stirring and dispersing time is 20-60 min. The high stirring speed in step (1) and step (2) also has a promoting effect on the improvement of the high voltage resistance of the power capacitor of the present application.

Further, the preparation method of the first polypropylene-based film specifically comprises the following steps:

(1) Mixing and dispersing carbon nano tubes, nano silicon dioxide, nano silicon carbide and butyl titanate, wherein the weight ratio of the carbon nano tubes to the nano silicon dioxide to the nano silicon carbide to the butyl titanate is 0.1: (1-5): (0.1-1): (1-10), mixing and dispersing at a stirring speed of 1000-3000 rpm for 1-2 hours at a temperature of 150-200deg.C to obtain a mixture;

(2) Mixing polypropylene, polyethylene and acrylonitrile-butadiene-styrene copolymer, wherein the weight ratio of the polypropylene to the polyethylene to the acrylonitrile-butadiene-styrene copolymer is 100: (20-30): (20-40), heating to a molten state, then adding the mixture prepared in the step (1) and the silane coupling agent, stirring and dispersing at a speed of 3000-5000 rpm, stirring and dispersing for 20-60 min, wherein the weight ratio of the polypropylene to the mixture prepared in the step (1) to the silane coupling agent is 100: (10-30): (8-35), pressurizing, extruding, cooling, and then biaxially stretching to obtain the first polypropylene base film.

Further, in the step (2), at least one of an antioxidant and an ultraviolet absorber is added together with the silane coupling agent.

Further, in the step (1), polyvinylidene fluoride is added simultaneously with butyl titanate. The addition of polyvinylidene fluoride helps to further improve the high voltage resistance of polypropylene based films for use in power capacitors.

Further, in the step (1), the addition amount of the polyvinylidene fluoride is 0.5-2% of the weight of the butyl titanate.

In the preparation method of the first polypropylene-based film and the second polypropylene-based film, butyl titanate modified carbon nano tube, nano silicon dioxide and nano silicon carbide are utilized to prepare a mixture; and then the mixture is used for carrying out compatibility modification on an organic system formed by polypropylene, polyethylene and acrylonitrile-butadiene-styrene copolymer, on the basis of polypropylene, the polyethylene and the acrylonitrile-butadiene-styrene copolymer are introduced and the mixture prepared in the step (1) is used for carrying out comprehensive modification, so that the compatibility of each component is skillfully improved, inorganic matters are uniformly dispersed in a system formed by the organic matters and having a space network structure, and particularly, the properties of the carbon nano tube, nano silicon dioxide and nano silicon carbide modified by butyl titanate are fully utilized, and finally the polypropylene-based film with good performance is prepared. The polypropylene base film is applied to a power capacitor, and can obviously improve the high voltage resistance of the power capacitor. And the application adopts an anhydrous system to prepare the polypropylene-based film, and has obvious improvement effect on improving the high voltage resistance of the power capacitor compared with a system with water.

The beneficial effects of the application are as follows:

according to the application, the first detection column and the second detection column are arranged, and the detection wire is wound around the capacitor core body, so that the judgment of the health condition of the capacitor core body is realized by judging whether the detection wire is disconnected or not. Thereby realizing rapid judgment of the internal condition of the power capacitor. When the inside of power capacitor goes wrong, can learn fast through first detection post and second detection post, the detection circuit of outside of being convenient for in time breaks off the power capacitor and external load's electric connection. Thereby avoiding the influence of the power capacitor on the external load.

According to the energy storage film capacitor, the first polypropylene composite film and the second polypropylene composite film are arranged, and in the preparation method of the first polypropylene film and the second polypropylene film, butyl titanate modified carbon nano tubes, nano silicon dioxide and nano silicon carbide are utilized to prepare a mixture; and then the mixture is used for carrying out compatibility modification on an organic system formed by polypropylene, polyethylene and acrylonitrile-butadiene-styrene copolymer, on the basis of polypropylene, the polyethylene and the acrylonitrile-butadiene-styrene copolymer are introduced and the mixture prepared in the step (1) is used for carrying out comprehensive modification, so that the compatibility of each component is skillfully improved, the inorganic matters are uniformly dispersed in a system formed by the organic matters and provided with a space network structure, and the properties of the carbon nano tube, nano silicon dioxide and nano silicon carbide modified by butyl titanate are fully utilized, so that the polypropylene base film with good performance is finally prepared. The polypropylene base film is applied to a power capacitor, and can obviously improve the high voltage resistance of the power capacitor.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is evident that the drawings described are only some embodiments of the application, but not all embodiments, and that other designs and drawings can be obtained from these drawings by a person skilled in the art without inventive effort.

Fig. 1 is a schematic diagram of the internal structure of a power capacitor;

fig. 2 is a schematic structural view of the outside of the power capacitor.

Detailed Description

The conception, specific structure, and technical effects produced by the present application will be clearly and completely described below with reference to the embodiments and the drawings to fully understand the objects, features, and effects of the present application. It is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present application based on the embodiments of the present application. In addition, all coupling/connection relationships mentioned herein do not refer to direct connection of the components, but rather, refer to the fact that a more optimal coupling structure may be formed by adding or subtracting coupling aids depending on the particular implementation. The technical features in the application can be interactively combined on the premise of no contradiction and conflict.

The present embodiment provides a power capacitor including: the capacitor comprises a containing shell 100, a sealing cover 200, a first lead-out tab 101, a second lead-out tab 102, a first wire, a second wire, a first detection column 131, a second detection column 132, a detection wire 120, a capacitor core 110 and surface insulation paper; the surface insulating paper is used for wrapping the outer peripheral surface of the capacitor core 110; the first lead tab 101, the second lead tab 102, the first detection post 131 and the second detection post 132 are embedded in the cover 200.

The capacitor core 110 falls into the accommodating case 100, and the capacitor core 110 includes a first polypropylene composite film and a second polypropylene composite film; the first polypropylene composite film and the second polypropylene composite film are parallel and coaxially rolled to form a capacitor roll shape; the first polypropylene composite film comprises: a first polypropylene-based film, the surface side of which is plated with a first metal layer; the second polypropylene composite film includes: a second polypropylene-based film, the surface side of which is plated with a second metal layer; the first polypropylene-based film and the second polypropylene-based film are wound in parallel and in the same direction, wherein the second polypropylene-based film is positioned between the second metal layer and the first metal layer; the first metal layer is connected with the first lead-out tab 101 through a first wire, and the second metal layer is connected with the second lead-out tab 102 through a second conductor; one end of the sensing wire 120 is connected to the first sensing post 131, and the other end of the sensing wire 120 is wound along the surface insulation paper on the outer circumferential wall of the capacitor core 110 and is finally connected to the second sensing post 132; the cover 200 seals the accommodating case 100.

The power capacitor of the application has the function of detecting the internal condition of the power capacitor. Wherein, when the inside of the power capacitor is in normal operation, i.e., when the capacitor core 110 is not overheated to expand. Can be connected to the first and second detection columns 131 and 132 through an external detection circuit. Since the capacitor chip is not expanded due to overheating, the sensing wire 120 wound around the outer circumferential wall of the capacitor chip is normal. Therefore, at the time of conductivity detection of the first detection column 131 and the second detection column 132, it can be found that the first detection column 131 and the second detection column 132 are conductive. Thus, it can be confirmed that the capacitor core 110 is normal and does not expand due to overheating. The interior of the power capacitor is normally operational.

When the inside of the power capacitor does not normally operate, most of all, the capacitor core 110 is overheated, thereby causing the capacitor core 110 to expand. At this time, since the capacitor core 110 expands, the sensing wire 120 wound around the outer circumferential wall of the capacitor core 110 is pulled and broken due to the expansion of the capacitor core 110. At this time, when the conductivity of the first and second detection columns 131 and 132 is detected, the first and second detection columns 131 and 132 cannot be conducted due to the breakage of the detection wire 120. For this reason, it can be confirmed that the capacitor core 110 is abnormal. The external detection circuit can timely disconnect the power capacitor from the external load. Thereby avoiding the influence of the power capacitor on the external load.

The application realizes the judgment of the health condition of the capacitor core 110 by arranging the first detection column 131 and the second detection column 132 and judging whether the detection wire 120 is disconnected or not by utilizing the mode that the detection wire 120 is wound around the capacitor core 110. Thereby realizing rapid judgment of the internal condition of the power capacitor. When the inside of the power capacitor is problematic, the first detection column 131 and the second detection column 132 can be used for quickly obtaining information, so that the external detection circuit can be conveniently and timely disconnected from the power capacitor and the external load. Thereby avoiding the influence of the power capacitor on the external load.

In some further embodiments, the first detecting post 131 is made of copper alloy. The second detecting post 132 is made of copper alloy.

In some further embodiments, the first lead tab 101 is provided with a first through hole 111. The second lead tab 102 is provided with a second through hole 122. By providing the first through hole 111, the first lead tab 101 is facilitated to be connected and mounted with an external circuit. The second through hole 122 is provided to facilitate connection and installation of the second lead tab 102 with an external circuit.

The power capacitor in the prior art is poor in high-voltage resistance and easy to break down, and even if the power capacitor is improved, the breakdown voltage of the corresponding polypropylene base film is difficult to exceed 5400KV/cm. This adversely affects the safety of the power capacitor in a high-voltage operating environment. Accordingly, it is desirable to provide a power capacitor that can withstand higher voltages.

The preparation of the first polypropylene-based film is described in detail below by way of a number of specific examples:

the starting materials, reagents or apparatus used in the following examples are all available from conventional commercial sources or may be obtained by methods known in the art unless otherwise specified.

Example 1: preparation of first Polypropylene-based film

The preparation method of the first polypropylene base film specifically comprises the following steps:

(1) Mixing and dispersing carbon nano tubes, nano silicon dioxide, nano silicon carbide and butyl titanate, wherein the weight ratio of the carbon nano tubes to the nano silicon dioxide to the nano silicon carbide to the butyl titanate is 0.1:1:1:6, mixing and dispersing at a stirring speed of 2000 rpm for 1 hour, and cooling to a room temperature of 25 ℃ at a temperature of 180 ℃ to obtain a mixture;

(2) Mixing polypropylene, polyethylene and acrylonitrile-butadiene-styrene copolymer, wherein the weight ratio of the polypropylene to the polyethylene to the acrylonitrile-butadiene-styrene copolymer is 100:20:40, heating to a molten state, then adding the mixture prepared in the step (1) and the silane coupling agent (vinyl triethoxysilane), stirring and dispersing, wherein the stirring and dispersing speed is 4000 rpm, the stirring and dispersing time is 40 minutes, and the weight ratio of the polypropylene to the mixture prepared in the step (1) to the silane coupling agent is 100:20:30, pressurizing, extruding, cooling in an extruder, and then biaxially stretching (pressurizing, extruding, cooling, biaxially stretching are conventional processes in the art) to obtain the first polypropylene-based film.

Example 2: preparation of first Polypropylene-based film

(1) Mixing and dispersing carbon nano tubes, nano silicon dioxide, nano silicon carbide and butyl titanate, wherein the weight ratio of the carbon nano tubes to the nano silicon dioxide to the nano silicon carbide to the butyl titanate is 0.1:4:0.5:10, mixing and dispersing at a stirring speed of 3000 r/min for 1 hour at 190 ℃ to obtain a mixture;

(2) Mixing polypropylene, polyethylene and acrylonitrile-butadiene-styrene copolymer, wherein the weight ratio of the polypropylene to the polyethylene to the acrylonitrile-butadiene-styrene copolymer is 100:25:30, heating to a molten state, then adding the mixture prepared in the step (1) and the silane coupling agent (vinyl triethoxysilane), stirring and dispersing, wherein the stirring and dispersing speed is 5000 r/min, the stirring and dispersing time is 40 min, and the weight ratio of the polypropylene to the mixture prepared in the step (1) to the silane coupling agent is 100:20:25, pressurizing, extruding, cooling, and then biaxially stretching to obtain the first polypropylene base film.

Example 3: preparing a first polypropylene base film;

in comparison with example 1, in example 3, polyvinylidene fluoride was also added in the step (1) in an amount of 0.8% by weight based on the weight of butyl titanate, and the rest was the same as in example 1.

Example 4: preparing a first polypropylene base film;

in comparison with example 1, the stirring speed of the mixing dispersion in step (1) of example 4 was 100 rpm, the stirring dispersion speed in step (2) was 200 rpm, and the other processes were the same as in example 1.

Comparative example 1;

the only difference of comparative example 1 compared with example 1 is that the same amount of carbon nanotubes, nano silica, nano silicon carbide was directly added in comparative example 1, i.e., butyl titanate was not added in comparative example 1, and the rest of the procedure was the same as in example 1.

Comparative example 2;

comparative example 2 is different from example 1 only in that the same amount of silane coupling agent was used instead of butyl titanate in step (1) of comparative example 2, and no nano silicon carbide was added, and the rest of the procedure was the same as in example 1.

Comparative example 3;

the difference in comparative example 3 compared with example 1 is only that the acrylonitrile-butadiene-styrene copolymer in example 1 was replaced with polypropylene in step (2) of comparative example 3, and the rest of the procedure was the same as in example 1.

And (3) testing the product effect:

the first polypropylene-based films prepared in examples 1 to 4 and comparative examples 1 to 3 were assembled into power capacitors, respectively, and the power capacitors were subjected to breakdown strength test (test with a program-controlled withstand voltage tester) according to a conventional method, and the results are shown in table 1.

TABLE 1

As can be seen from Table 1, the first polypropylene-based films produced in examples 1 to 4 all have significantly higher breakdown strength than the power capacitors produced in comparative examples 1 to 3. The modified butyl titanate is adopted to modify the carbon nano tube, the nano silicon dioxide and the nano silicon carbide, so that the high voltage resistance of the power capacitor can be obviously improved when the prepared polypropylene base film is applied to the power capacitor.

From the results of examples 1 and 3, it can be seen that the addition of polyvinylidene fluoride can further increase the high voltage resistance of the power capacitor when the polypropylene-based film is applied to the power capacitor.

From the results of example 1 and example 4, it can be seen that the stirring speed has a great influence on the product properties during the preparation of the polypropylene-based film.

While the preferred embodiment of the present application has been illustrated in detail, the application is not limited to the embodiments described, and various equivalent modifications and substitutions can be made by one skilled in the art without departing from the spirit of the application, and these are intended to be included within the scope of the present application as defined in the appended claims.

Claims

1. A power capacitor, comprising: the capacitor comprises a containing shell, a sealing cover, a first lead-out tab, a second lead-out tab, a first lead, a second lead, a first detection column, a second detection column, a detection wire, a capacitor core body and surface insulation paper; the surface insulating paper is used for wrapping the outer peripheral surface of the capacitor core body;

the first polypropylene composite film comprises: a first polypropylene-based film, the surface side of which is plated with a first metal layer; the second polypropylene composite film includes: a second polypropylene-based film, the surface side of which is plated with a second metal layer; the first polypropylene-based film and the second polypropylene-based film are wound in parallel and in the same direction, wherein the second polypropylene-based film is positioned between the second metal layer and the first metal layer; the first metal layer is connected with the first lead-out tab through a first lead wire, and the second metal layer is connected with the second lead-out tab through a second conductor; one end of the detection wire is connected with the first detection column, and the other end of the detection wire is wound along the surface insulating paper on the peripheral wall of the capacitor core body and is finally connected with the second detection column; the cover seals the accommodating case;

the preparation method of the first polypropylene base film is the same as the preparation method of the second polypropylene base film, and specifically comprises the following steps:

2. A power capacitor according to claim 1, wherein the first sensing post is a copper alloy material.

3. A power capacitor according to claim 1, wherein the second sensing post is a copper alloy material.

4. A power capacitor according to claim 1, wherein the first lead tab is provided with a first through hole.

5. A power capacitor according to claim 1, wherein the second lead tab is provided with a second through hole.

6. The power capacitor of claim 1, wherein in the step (1), the weight ratio of the carbon nanotubes, the nano silicon dioxide, the nano silicon carbide and the butyl titanate is 0.1: (1-5): (0.1-1): (1-10).

7. A power capacitor according to claim 1, wherein in step (1), the stirring speed of the mixing dispersion is 1000 to 3000 rpm, and the time of the mixing dispersion is 1 to 2 hours; in the step (1), the temperature of mixing and dispersing is 150-200 ℃; in the step (2), the stirring and dispersing speed is 3000-5000 r/min, and the stirring and dispersing time is 20-60 min.

8. A power capacitor according to claim 1, characterized in that the preparation method of the first polypropylene-based film specifically comprises the steps of:

9. A power capacitor according to claim 1, wherein in step (1), polyvinylidene fluoride is added together with butyl titanate; the addition amount of the polyvinylidene fluoride is 0.5-2% of the weight of the butyl titanate.